End ring for squirrel-cage windings.



Patented Feb 6, 1917.

F. M. WHITNEY.

APPLICATION FILED MAY 28, I914.

END RING FOR SQLIIR REL CAGE WINDINGSI Alva/70R BYFH AND/5M WH/ TNE Y, m I

firsi ir TD'RNEY,

WT/VE55E5 UNITED STATES PATENT OFFICE.

FRANCIS M. WHITNEY, OF. SAN DIEGO, CALIFORNIA, ASSIGNOR T GENERArL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

\END BING- IOR SQUIBBEL-CAGE WINDINGS.

Specification 0! Letters Patent.

Patented Feb. 6, 1917.

Application filed May as. 1914. Serial no. 841,035.

State of California, have invented certain new and useful Imprbvements in End Rings for Squirrel-Cage Windings, of which the following is a specification.

My invention relates to squirrel cage windings for dynamo electric machines, and more especially to an end ring construction for such windings and the method of applying the same.

The usual end ring constructions are of such form that theypequire special tools either for their application or theirmanufacture. It is desirable, however, that the construction of the end ring for a squirrel cage winding should be such that it can be easily repaired or replaced by means of ordinary tools and from easily obtained material. Such a need is especially apparent in the smaller sizes of induction motors with squirrel cage secondaries.

The object of my invention is, then, to provide novel construction of an end ring for a squirrel cage winding, and also a novel method of securing the same to the bars of the winding, which is simple, ellicient and capable of being carried out with the aid of ordinary tools and common materials.

My invention will be more readily understood by reference to the accompanying drawing, in which:

Figure l is a radial section of the rotor of an induction motor showing the method of application of my end ring construction at the right, and the finished product at the left.

Fig. 2 is a fragmental end view of the finished construction with a portion of the outer annular member broken away.

In the construction shown, the rotor 1 is provided with the customary laminated core 2 in which are placed the conductor bars 3. The bars 3 are shown as of substantially rectangular cross-section, and while this is not absolutely essential, it will be preferable for the application of my invention. .At the left side of Fig. 1 the completed end ring is shown consist of a flanged annular member and a similar flanged annular member 5, engaging the inner and outer peripheries of the conductor bars, one of the annular members forcing the bars into engagement with the other annular member, whereby good electrical contact is obtained between the bars and the end ring. These annular members are preferably formed of sheet copper and may be conveniently made by the use of a spinning lathe. I have found that for end rings to be applied to induction motors of 10 or 20 H. P., sheet copper of about #16 gage is suitable.

The annular member 4, comprising a transverse flange 6 and a radial flange 7, is' made of such a diameter that it will exactly fit the inner periphery of the conductor bars.

When first placed in position it is pushed back from the ends of these bars, and the bars then bent toward the member 4:, as indicated at 3, by being lightly tapped with a hammer. By these processes, it will be seen that the diameter of the outer periphery of the bars is slightly reduced. The other annular member 5, similarly constructed with a transverse flange 8 and a radial flange 9, is made of such a size that the inner diameter of the flange 8 is slightly less than the normal diameter of the outer periphery of the bars. When the diameter of said outer periphery has been reduced in the manner described, however, this annular member 5 will exactly fit over the outer. ends of the bars. If, now, the member 4: is forced outwardly toward the ends of the bars until it is in the same plane as the member 5, it willbe seen that the bars will be forced by flange 6 into engagement with flange 8 and consequently will be tightly gripped between the transverse flanges 6 and 8, because the difference of the radii of the engaging surfaces of these flanges before their application to the bars 3 is slightly less than. the radial thickness of the bars. The process of forcing the member a outwardly may be carried on in any convenient manner, as by inserting some blunt ended tool between the conductor bars and against the flange i and then li htly tapping the tool with a hammer. his process will, of course, be carried on progressively around the circumference of the rotor. Still another manner of forcing out the member 4 is illustrated at the right side of Fig. 1, where a clamp 10 engages the radial flanges '3" and By providing a suitable number of such clamps and tightening them in unison, the member 4' would be drawn outwardly until it is contiguous with the member 5.

By this means I have provided a simple construction of end ring which may be easily manufactured and applied by the use of my novel method with the ordinary tools to be found in a repair shop. The end ring will be frictionally held on the conductor bars, and the application of any solder is unnecessary, in order to secure good electrical contact therebetween. If desired, however, I may fill the spaces between the conductor bars within the flanges 6 and 8 with melted solder or melted brass. Such an artifice will add to the rigidity of the construction and the conductivity of the ring. An inspection of the left hand side of Fig. 1 will show that if the flanges 6 and 8 of the annular members aremade-ef equal widths, that of the member 4 will be slightly closer to the core 2 of the rotor; Consequently, if the rotor is placed on end in order to pour in the melted solder or brass, any surplus metal will flow over the outside.

I conceive that various modifications of the particular form of annular members are posslble, as well as of the particular manner of bringing said annular members into the same plane, and I, accordingly, do not desire to be limited to the exact construction or method of application illustrated and described, but seek to cover in the appended claims all those modifications and equivalent constructions which fall within the true scope and spirit of my invention.

What I claim as new and desire to secureby Letters Patent of the United States, is 2- 1. A squirrel cage winding comprising conductor bars of substantially rectangular cross section, and an end ring connecting said bars comprising two annular members each provided with a transverse flange, the flange on one of said members engaging one periphery of said bars, the flange on the other of said bars engaging the other periphery of said bars in substantially the same plane as said first mentioned flange and forcing said bars into engagement therewith, said annular members being also provided with radial flanges, one of which overhangs the ends of said bars and the other of which is contiguous thereto and in electrical con-' tact therewith.

2. A squirrel cage winding, comprising conductor bars of substantially rectangular cross section, and an end ring connecting said bars comprising two annular members each provided with a transverse flange, the flange on one of said-members engaging the outer periphery of said bars, the flange on the other of said membersfe'ngaging the inner periphery of said bars in substantially the same plane as said first mentioned flange and forcing said bars into engagement therewith, said annular members bemg also provided with radial flanges one of which overhangs the ends of said bars and the other of which is contiguous thereto and in elecmal diameter of the periphery of the bars to which it is applied, and then forcing the two members into substantially the same plane, whereby the bars are tightly gripped therebetween.

4:. The method securing an end ring to the bars of a squirrel cage winding, which consists in placing an annular member in engagement with the inner periphery of said bars, away from the ends thereof, slightly bending the ends of said bars inwardly, applying another annular member over the bent ends of said bars, the difierence in the radii of the engaging surfaces of said annular members being slightly less than the radial thickness of said bars, and then forcing the two members into substantially the same plane, whereby said members are tightly held in engagement with said bars.

In witness whereof, I have hereunto set my hand this 19th day of May, 1914:.

FRANCIS M. WHITNEY. Witnesses:

. Emma WILLIAMSON,

R. A. WRIGHT. 

